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arXiv 1005.4565math.APphysics.ao-ph
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两流体界面稳定性判据及其应用

A stability criterion for two-fluid interfaces and applications

David Lannes

摘要:

本文导出了一个新的双流体界面稳定性判据。这个标准确保了“稳定”的本地解决方案的存在,不打破太快,由于开尔文-亥姆霍兹不稳定性。它既可以看作是瑞利-泰勒准则的二流体推广,也可以看作是开尔文稳定性条件的非线性版本。我们表明,重力可以控制惯性效应的剪切频率是足够高的表面张力发挥相关的作用。这就解释了为什么表面张力是一个必要条件适定性,而(低频)的主要动力学的界面波是不受它。为了得到一个实用的版本,这个标准,我们的工作与无量纲版本的方程,并允许各种渐近制度的可能性,如浅水限制。这个极限是奇异的,我们必须得到一个新的符号分析的狄利克雷-诺依曼算子,其中包括一个无限平滑的“尾巴”占底部的贡献。然后,我们验证我们的标准与实验数据比较在两个重要的设置:空气-水界面和内波。我们观察到的良好的协议,使我们能够讨论的情况下,波破碎和水-盐水界面的行为。我们还展示了如何严格证明用于应用程序的两流体渐近模型,以及如何将它们的一些属性与开尔文-亥姆霍兹不稳定性联系起来。

英文摘要:

We derive here a new stability criterion for two-fluid interfaces. This criterion ensures the existence of "stable" local solutions that do no break down too fast due to Kelvin-Helmholtz instabilities. It can be seen both as a two-fluid generalization of the Rayleigh-Taylor criterion and as a nonlinear version of the Kelvin stability condition. We show that gravity can control the inertial effects of the shear up to frequencies that are high enough for the surface tension to play a relevant role. This explains why surface tension is a necessary condition for well-posedness while the (low frequency) main dynamics of interfacial waves is unaffected by it. In order to derive a practical version of this criterion, we work with a nondimensionalized version of the equations and allow for the possibility of various asymptotic regimes, such as the shallow water limit. This limit being singular, we have to derive a new symbolic analysis of the Dirichlet-Neumann operator that includes an infinitely smoothing "tail" accounting for the contribution of the bottom. We then validate our criterion by comparison with experimental data in two important settings: air-water interfaces and internal waves. The good agreement we observe allows us to discuss the scenario of wave breaking and the behavior of water-brine interfaces. We also show how to rigorously justify two-fluid asymptotic models used for applications and how to relate some of their properties to Kelvin-Helmholtz instabilities.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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